Substances, such as foods, that easily spoil are stored or transported in a refrigerated state. In this case, when storage temperature is changed or food is exposed to the outside, the food may go bad. If it is possible to determine whether or not the food is kept refrigerated well until the food exposed to the outside is finally used, food poisoning or the like resulting from growth of putrefying bacteria can be prevented and safety of food can be effectively managed.
It is possible to chemically or physically measure and display a change history in exterior air over time during food storage. Although it is possible to physically measure time and degree through change in temperature of the exterior environment, but it is more difficult to individually measure how much the temperature of liquid food changes through the substance in a storage container due to various factors such as conditions of a storage area and heat transfer capacity of the storage container.
It is more difficult to determine storage temperature, exposure time and the like in order to determine if stored food spoils or not. It is more difficult to biologically determine if putrefying bacteria grow or not based on various types of temperature changes than to physically measure temperature changes. It is possible to predict the time and temperature required for growth of putrefying bacteria, but it is impossible to physically and chemically predict whether putrefying bacteria actually grow or not via continuously changed temperatures and different exposure times in food storage areas.
A label that can be attached to the outside of a food storage container containing lyophilized organic acid, a medium powder, a pH indicator and distilled water is produced and is used to determine whether or not a stored substance spoils depending on cumulative temperature changes.
Korean Patent Laid-open No. 2002-86597 discloses a system for displaying time and temperature suitable for activation and Korean Patent No. 1012125 discloses a label for determining growth of food putrefying bacteria depending on cumulative storage temperature changes.